The long term goal of the proposed research is to discover key biochemical events in the physiology of H. capsulatum which regulate various expressions of growth and morphogenesis in this dimorphic zoopathogen. Ultimately such discoreries will provide new avenues of approach to successful therapy in histoplasmosis. The long term goal will be pursued by: (a) studying amino acid transport and its inhibition by analogues, (b) observing the effects of inhibitors on macromolecular syntheis, (c) examining blastospore germination as one key morphogenetic event in the life cycle of the fungus, (d) isolating nutritional and temperature sensitive mutants, and (e) studies of growth factors essential to blastospore replication.